Don't allow LTI tool to be larger than its modal
Don't allow LTI tool to be larger than its modal

This can make scroll bars disappear and make content inside the iframe
inaccessible.

closes PLAT-5641
flag=none

(This is affecting Wiley / some large universities to Karl wants this deployed soon via the covid branch)

Test plan:
- launch an LTI tool modal in the following ways. The LTI 1.3 test tool
  works for this because it has content that is taller than the modal,
  although you could probably inspect element and add content to make it
  taller too.
  - tool installed with link_selection -- goto modules, add an item,
    choose External Tool
  - tool installed in RCE context (note, when changing the height there,
    there may be 2 scrollbars sometimes, but I tried before this commit
    and the behavior was the same)
  - other places that support deep linking??
- inspect element on something inside the iframe and run the following
  in the JS console. The iframe should never be taller than the modal,
  meaning there should always be scroll bars and all content should be
  visible. (Note: after each call you may have to inspect element on
  something in the iframe again to get inside the context of the iframe
  page)
    parent.postMessage('{"subject":"lti.frameResize", "height":"10000px}', '*')
    parent.postMessage('{"subject":"lti.frameResize", "height":2000}', '*')
    parent.postMessage('{"subject":"lti.frameResize", "height":100}', '*')
    parent.postMessage('{"subject":"lti.frameResize", "height":"200px"}', '*')

Change-Id: Icf4b85b926e6acedf5873981e0bd15ef3d074d93
(cherry picked from commit d981d1248b42c6a4a23a334e40a8a077976ea9e3)
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/232603
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Product-Review: KC Naegle <9fbecd016338f9910821a8a5d5d0ae4fc9abfaa5@instructure.com>
Reviewed-by: Weston Dransfield <e9203059795dc94e28a8831c65eb7869e818825e@instructure.com>
QA-Review: Weston Dransfield <e9203059795dc94e28a8831c65eb7869e818825e@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms